DxTerity Diagnostics will develop a rapid, cost-effective prototype assay for measurement of radiation toxicity in blood using its innovative DxDirect technology. The assay will be based on the gene expression response signature of blood cells to radiation exposure ex vivo, and will not require purification of RNA prior to analysis. RNA targets will be selected based on gene expression profiling of normal and radiosensitive lymphoblast cell lines and bioinformatic analysis of prior microarray studies. The assay will used to measure whole blood gene expression responses to ex vivo irradiation in 100 prospective blood samples from radiotherapy patients. Expression results will be correlated with clinical symptoms of radiation toxicity, and the most informative genes for radiation toxicity will be used to design a companion diagnostic test for radiation therapy. The long-term goal is to identify patients prior to therapy who may be at risk of radiotoxicity. This test will be established in DxTeritys CLIA-compliant clinical laboratory, optimized and validated prior to transfer of the SOP to the NCI. The resulting test will be the first practical and cost-effective test to reduce complications from the radiotherapeutic treatment of malignancies and can be piloted in larger multi-center clinical trials.